U.S. patent application number 14/239808 was filed with the patent office on 2014-06-19 for tempered glass and method for producing same.
The applicant listed for this patent is Takashi Murata, Takako Tojyo. Invention is credited to Takashi Murata, Takako Tojyo.
Application Number | 20140170380 14/239808 |
Document ID | / |
Family ID | 47746418 |
Filed Date | 2014-06-19 |
United States Patent
Application |
20140170380 |
Kind Code |
A1 |
Murata; Takashi ; et
al. |
June 19, 2014 |
TEMPERED GLASS AND METHOD FOR PRODUCING SAME
Abstract
A tempered glass of the present invention is a tempered glass
having a compression stress layer in a surface thereof, the
tempered glass comprising, as a glass composition in terms of mol
%, 45 to 75% of SiO.sub.2, 3 to 15% of Al.sub.2O.sub.3, 0 to 12% of
Li.sub.2O, 0.3 to 20% of Na.sub.2O, 0 to 10% of K.sub.2O, and 1 to
15% of MgO+CaO, and having a molar ratio
(Al.sub.2O.sub.3+Na.sub.2O+P.sub.2O.sub.5)/SiO.sub.2 of 0.1 to 1, a
molar ratio (B.sub.2O.sub.3+Na.sub.2O)/SiO.sub.2 of 0.1 to 1, a
molar ratio P.sub.2O.sub.5/SiO.sub.2 of 0 to 1, a molar ratio
Al.sub.2O.sub.3/SiO.sub.2 of 0.01 to 1, and a molar ratio
Na.sub.2O/Al.sub.2O.sub.3 of 0.1 to 5, characterized in that the
surface or an end surface of the tempered glass is etched after
tempering treatment.
Inventors: |
Murata; Takashi; (Shiga,
JP) ; Tojyo; Takako; (Shiga, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Murata; Takashi
Tojyo; Takako |
Shiga
Shiga |
|
JP
JP |
|
|
Family ID: |
47746418 |
Appl. No.: |
14/239808 |
Filed: |
August 17, 2012 |
PCT Filed: |
August 17, 2012 |
PCT NO: |
PCT/JP2012/070921 |
371 Date: |
February 20, 2014 |
Current U.S.
Class: |
428/141 ;
428/410; 65/30.14 |
Current CPC
Class: |
C03C 3/087 20130101;
C03C 3/097 20130101; C03C 3/11 20130101; C03C 15/00 20130101; Y10T
428/24355 20150115; Y10T 428/315 20150115; C03B 33/02 20130101;
C03C 21/002 20130101 |
Class at
Publication: |
428/141 ;
428/410; 65/30.14 |
International
Class: |
C03C 3/11 20060101
C03C003/11; C03C 3/097 20060101 C03C003/097; C03C 21/00 20060101
C03C021/00; C03B 33/02 20060101 C03B033/02; C03C 15/00 20060101
C03C015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 23, 2011 |
JP |
2011-181807 |
Claims
1. A tempered glass having a compression stress layer in a surface
thereof, the tempered glass comprising, as a glass composition in
terms of mol %, 45 to 75% of SiO.sub.2, 3 to 15% of
Al.sub.2O.sub.3, 0 to 12% of B.sub.2O.sub.3, 0 to 12% of Li.sub.2O,
0.3 to 20% of Na.sub.2O, 0 to 10% of K.sub.2O, 1 to 15% of MgO+CaO,
and 0 to 10% of P.sub.2O.sub.5, and having a molar ratio
(Al.sub.2O.sub.3+Na.sub.2O+P.sub.2O.sub.5)/SiO.sub.2 of 0.1 to 1, a
molar ratio (B.sub.2O.sub.3+Na.sub.2O)/SiO.sub.2 of 0.1 to 1, a
molar ratio P.sub.2O.sub.5/SiO.sub.2 of 0 to 1, a molar ratio
Al.sub.2O.sub.3/SiO.sub.2 of 0.01 to 1, and a molar ratio
Na.sub.2O/Al.sub.2O.sub.3 of 0.1 to 5, wherein the surface or an
end surface of the tempered glass is etched after tempering
treatment.
2. The tempered glass according to claim 1, wherein the tempered
glass comprises, as a glass composition in terms of mol %, 45 to
75% of SiO.sub.2, 4 to 13% of Al.sub.2O.sub.3, 0 to 3% of
B.sub.2O.sub.3, 0 to 8% of Li.sub.2O, 5 to 20% of Na.sub.2O, 0.1 to
10% of K.sub.2O, 3 to 13% of MgO+CaO, and 0 to 10% of
P.sub.2O.sub.5, and has a molar ratio
(Al.sub.2O.sub.3+Na.sub.2O+P.sub.2O.sub.5)/SiO.sub.2 of 0.1 to 0.7,
a molar ratio (B.sub.2O.sub.3+Na.sub.2O)/SiO.sub.2 of 0.1 to 0.7, a
molar ratio P.sub.2O.sub.5/SiO.sub.2 of 0 to 0.5, a molar ratio
Al.sub.2O.sub.3/SiO.sub.2 of 0.01 to 0.7, and a molar ratio
Na.sub.2O/Al.sub.2O.sub.3 of 0.5 to 4.
3. The tempered glass according to claim 1, wherein the tempered
glass comprises, as a glass composition in terms of mol %, 45 to
75% of SiO.sub.2, 5 to 12% of Al.sub.2O.sub.3, 0 to 1% of
B.sub.2O.sub.3, 0 to 4% of Li.sub.2O, 8 to 20% of Na.sub.2O, 0.5 to
10% of K.sub.2O, 5 to 13% of MgO+CaO, and 0 to 10% of
P.sub.2O.sub.5, and has a molar ratio
(Al.sub.2O.sub.3+Na.sub.2O+P.sub.2O.sub.5)/SiO.sub.2 of 0.1 to 0.5,
a molar ratio (B.sub.2O.sub.3+Na.sub.2O)/SiO.sub.2 of 0.1 to 0.5, a
molar ratio P.sub.2O.sub.5/SiO.sub.2 of 0 to 0.3, a molar ratio
Al.sub.2O.sub.3/SiO.sub.2 of 0.05 to 0.5, and a molar ratio
Na.sub.2O/Al.sub.2O.sub.3 of 1 to 3.
4. The tempered glass according to claim 1, wherein the tempered
glass comprises, as a glass composition in terms of mol %, 45 to
75% of SiO.sub.2, 5 to 11% of Al.sub.2O.sub.3, 0 to 1% of
B.sub.2O.sub.3, 0 to 4% of Li.sub.2O, 9 to 20% of Na.sub.2O, 0.5 to
8% of K.sub.2O, 0 to 12% of MgO, 0 to 3% of CaO, 5 to 12% of
MgO+CaO, and 0 to 10% of P.sub.2O.sub.5, and has a molar ratio
(Al.sub.2O.sub.3+Na.sub.2O+P.sub.2O.sub.5)/SiO.sub.2 of 0.1 to 0.5,
a molar ratio (B.sub.2O.sub.3+Na.sub.2O)/SiO.sub.2 of 0.1 to 0.3, a
molar ratio P.sub.2O.sub.5/SiO.sub.2 of 0 to 0.2, a molar ratio
Al.sub.2O.sub.3/SiO.sub.2 of 0.05 to 0.3, and a molar ratio
Na.sub.2O/Al.sub.2O.sub.3 of 1 to 3.
5. The tempered glass according to claim 1, wherein the tempered
glass comprises, as a glass composition in terms of mol %, 50 to
70% of SiO.sub.2, 5 to 11% of Al.sub.2O.sub.3, 0 to 1% of
B.sub.2O.sub.3, 0 to 2% of Li.sub.2O, 10 to 18% of Na.sub.20, 1 to
6% of K.sub.2O, 0 to 12% of MgO, 0 to 2.5% of CaO, 5 to 12% of
MgO+CaO, and 0 to 10% of P.sub.2O.sub.5, and has a molar ratio
(Al.sub.2O.sub.3+Na.sub.2O+P.sub.2O.sub.5)/SiO.sub.2 of 0.2 to 0.5,
a molar ratio (B.sub.2O.sub.3+Na.sub.2O)/SiO.sub.2 of 0.15 to 0.27,
a molar ratio P.sub.2O.sub.5/SiO.sub.2 of 0 to 0.1, a molar ratio
Al.sub.2O.sub.3/SiO.sub.2 of 0.07 to 0.2, and a molar ratio
Na.sub.2O/Al.sub.2O.sub.3 of 1 to 2.3.
6. The tempered glass according to claim 1, wherein a surface
roughness Ra of the etched surface is 1 nm or less.
7. The tempered glass according to claim 1, wherein a compression
stress value of the compression stress layer is 200 MPa or more,
and a depth of the compression stress layer is 10 .mu.m or
more.
8. The tempered glass according to claim 1, wherein the tempered
glass has an internal tensile stress of 1 to 200 MPa.
9. The tempered glass according to claim 1, wherein the tempered
glass has a liquidus temperature of 1,250.degree. C. or less.
10. The tempered glass according to claim 1, wherein the tempered
glass has a liquidus viscosity of 10.sup.4.0 dPas or more.
11. The tempered glass according to claim 1, wherein the tempered
glass has a temperature at 10.sup.4.0 dPas of 1,280.degree. C. or
less.
12. The tempered glass according to claim 1, wherein the tempered
glass has a temperature at 10.sup.2.5 dPas of 1,620.degree. C. or
less.
13. The tempered glass according to claim 1, wherein the tempered
glass has a density of 2.6 g/cm.sup.3 or less.
14. The tempered glass according to claim 1, wherein the tempered
glass is formed by a float method.
15. The tempered glass according to claim 1, wherein the tempered
glass is used for a touch panel display.
16. The tempered glass according to claim 1, wherein the tempered
glass is used for a cover glass for a cellular phone.
17-22. (canceled)
23. A production method for a tempered glass, comprising: a forming
step of melting glass raw materials blended to achieve a glass
composition comprising, in terms of mol %, 45 to 75% of SiO.sub.2,
3 to 15% of Al.sub.2O.sub.3, 0 to 12% of Li.sub.2O, 0.3 to 20% of
Na.sub.2O, 0 to 10% of K.sub.2O, and 1 to 15% of MgO+CaO, into
molten glass, followed by formation of the molten glass into a
glass sheet; a tempering step of forming a compression stress layer
by performing ion exchange treatment to yield a tempered glass; a
masking step of masking a surface of the tempered glass; and an
etching step of etching the tempered glass in an etching
liquid.
24. The production method for a tempered glass according to claim
23, further comprising a patterning step of performing patterning
on the surface of the tempered glass before the masking step.
25. The production method for a tempered glass according to claim
23, wherein the etching step comprises a step of separating the
tempered glass into a plurality of small tempered glass pieces.
26. The production method for a tempered glass according to claim
23, wherein the etching liquid comprises one kind or two or more
kinds selected from the group consisting of HF, HCl,
H.sub.2SO.sub.4, HNO.sub.3, NH.sub.4F, NaOH, and NH.sub.4HF.sub.2.
Description
TECHNICAL FIELD
[0001] The present invention relates to a tempered glass and a
production method for the same, and more particularly, to a
tempered glass suitable for a cover glass for a cellular phone, a
digital camera, a personal digital assistant (PDA), or a solar
cell, or a glass substrate for a display, in particular, a touch
panel display, and a production method for the same.
BACKGROUND ART
[0002] Devices such as a cellular phone, a digital camera, a PDA, a
touch panel display, a large-screen television, and a wireless
charging system tend to be more widely used.
[0003] A tempered glass produced by performing tempering treatment
such as ion exchange treatment is used in each of those devices
(see Patent Literature 1 and Non Patent Literature 1).
[0004] In conventional devices, there has been adopted a structure
in which a touch panel sensor is formed on a display module and a
tempered glass (protective member) is placed over the touch panel
sensor.
[0005] Further, although small devices such as a cellular phone
each have a size of 3 to 4 inches, tablet PCs and the like each
have a size of 9 to 10 inches. Thus, such devices as the tablet PCs
each involve the issues of how to reduce the mass of the device and
how to reduce the total thickness thereof.
[0006] In order to cope with those issues, a method involving
forming a touch panel sensor on a tempered glass (protective
member) has been adopted. In this case, the tempered glass
(protective member) is required to, for example, (1) have a high
mechanical strength, (2) have a liquidus viscosity suitable for,
for example, a down-draw method such as an overflow down-draw
method or a slit down-draw method and a float method, in order to
perform the mass production of large glass sheets, (3) have a
viscosity at high temperature suitable for being formed into a
shape, (4) have a low density, and (5) have a sufficiently high
strain point to prevent pattern shift from occurring at the time of
forming a tough panel film.
CITATION LIST
Patent Literature
[0007] Patent Literature 1: JP 2006-83045 A
Non Patent Literature
[0007] [0008] Non Patent Literature 1: Tetsuro Izumitani et al.,
"New glass and physical properties thereof," First edition,
Management System Laboratory. Co., Ltd., Aug. 20, 1984, p.
451-498
SUMMARY OF INVENTION
Technical Problem
[0009] By the way, when patterning is performed individually onto
each tempered glass having a size of 3 to 10 inches, the production
cost of a device using the tempered glass increases. In order to
cope with this problem, it is possible to adopt a method involving
performing a predetermined patterning onto a large tempered glass
and then cutting the large one into a plurality of small tempered
glass pieces with a laser.
[0010] However, this method involves a problem in that, when an R
process is applied to the four corners of each resultant laser-cut
tempered glass, or a notching process is applied to each long side
thereof or each short side thereof, the production cost of a device
using the tempered glass increases. When such a tempered glass is
used for applications such as a mobile terminal, this problem is
particularly serious.
[0011] On the other hand, when a large glass sheet is subjected to
tempering treatment, and a predetermined patterning and masking are
applied to the tempered glass sheet, and then etching in an etching
liquid is performed to separate the resultant into a plurality of
small tempered glass pieces, the above-mentioned problem can be
solved. However, it took a long time to apply etching to
conventional tempered glasses, possibly increasing the cost of each
resultant small tempered glass piece.
[0012] Thus, a technical object of the present invention is to
invent a tempered glass which satisfies the characteristics
conventionally required and can be easily separated into a
plurality of small tempered glass pieces by etching.
Solution to Problem
[0013] The inventors of the present invention have made various
studies and have consequently found that the technical object can
be achieved by strictly controlling the content range of each
component in a glass composition and etching the surface of glass
after tempering treatment. Thus, the finding is proposed as the
present invention. That is, a tempered glass of the present
invention is a tempered glass having a compression stress layer in
a surface thereof, the tempered glass comprising, as a glass
composition in terms of mol %, 45 to 75% of SiO.sub.2, 3 to 15% of
Al.sub.2O.sub.3, 0 to 12% of B.sub.2O.sub.3, 0 to 12% of Li.sub.2O,
0.3 to 20% of Na.sub.2O, 0 to 10% of K.sub.2O, 1 to 15% of MgO+CaO,
and 0 to 10% of P.sub.2O.sub.5, and having a molar ratio
(Al.sub.2O.sub.3+Na.sub.2O+P.sub.2O.sub.5)/SiO.sub.2 of 0.1 to 1, a
molar ratio (B.sub.2O.sub.3+Na.sub.2O)/SiO.sub.2 of 0.1 to 1, a
molar ratio P.sub.2O.sub.5/SiO.sub.2 of 0 to 1, a molar ratio
Al.sub.2O.sub.3/SiO.sub.2 of 0.01 to 1, and a molar ratio
Na.sub.2O/Al.sub.2O.sub.3 of 0.1 to 5, characterized in that the
surface or an end surface of the tempered glass is etched after
tempering treatment. Herein, the "MgO+CaO" refers to the total
amount of MgO and CaO. The
"Al.sub.2O.sub.3+Na.sub.2O+P.sub.2O.sub.5" refers to the total
amount of Al.sub.2O.sub.3, Na.sub.2O, and P.sub.2O.sub.5. The
"B.sub.2O.sub.3+Na.sub.2O" refers to the total amount of
B.sub.2O.sub.3 and Na.sub.2O, Note that, although the aspect that
the surfaces of the tempered glass (or small pieces thereof) of the
present invention are entirely etched is not completely excluded,
the aspect that the surfaces of the tempered glass (or small pieces
thereof) are partially etched or the aspect that the surfaces
thereof are not etched is preferred, when the gist of the present
invention is taken into consideration. Further, when the tempered
glass of the present invention is separated into small tempered
glass pieces each having a product shape by etching, the end
surfaces of the tempered glass usually are entirely etched.
[0014] Second, it is preferred that the tempered glass of the
present invention comprise, as a glass composition in terms of mol
%, 45 to 75% of SiO.sub.2, 4 to 13% of Al.sub.2O.sub.3, 0 to 3% of
B.sub.2O.sub.3, 0 to 8% of Li.sub.2O, 5 to 20% of Na.sub.2O, 0.1 to
10% of K.sub.2O, 3 to 13% of MgO+CaO, and 0 to 10% of
P.sub.2O.sub.5, and have a molar ratio
(Al.sub.2O.sub.3+Na.sub.2O+P.sub.2O.sub.5)/SiO.sub.2 of 0.1 to 0.7,
a molar ratio (B.sub.2O.sub.3+Na.sub.2O)/SiO.sub.2 of 0.1 to 0.7, a
molar ratio P.sub.2O.sub.5/SiO.sub.2 of 0 to 0.5, a molar ratio
Al.sub.2O.sub.3/SiO.sub.2 of 0.01 to 0.7, and a molar ratio
Na.sub.2O/Al.sub.2O.sub.3 of 0.5 to 4.
[0015] Third, it is preferred that the tempered glass of the
present invention comprise, as a glass composition in terms of mol
%, 45 to 75% of SiO.sub.2, 5 to 12% of Al.sub.2O.sub.3, 0 to 1% of
B.sub.2O.sub.3, 0 to 4% of Li.sub.2O, 8 to 20% of Na.sub.2O, 0.5 to
10% of K.sub.2O, 5 to 13% of MgO+CaO, and 0 to 10% of
P.sub.2O.sub.5, and have a molar ratio
(Al.sub.2O.sub.3+Na.sub.2O+P.sub.2O.sub.5)/SiO.sub.2 of 0.1 to 0.5,
a molar ratio (B.sub.2O.sub.3+Na.sub.2O)/SiO.sub.2 of 0.1 to 0.5, a
molar ratio P.sub.2O.sub.5/SiO.sub.2 of 0 to 0.3, a molar ratio
Al.sub.2O.sub.3/SiO.sub.2 of 0.05 to 0.5, and a molar ratio
Na.sub.2O/Al.sub.2O.sub.3 of 1 to 3.
[0016] Fourth, it is preferred that the tempered glass of the
present invention comprise, as a glass composition in terms of mol
%, 45 to 75% of SiO.sub.2, 5 to 11% of Al.sub.2O.sub.3, 0 to 1% of
B.sub.2O.sub.3, 0 to 4% of Li.sub.2O, 9 to 20% of Na.sub.2O, 0.5 to
8% of K.sub.2O, 0 to 12% of MgO, 0 to 3% of CaO, 5 to 12% of
MgO+CaO, and 0 to 10% of P.sub.2O.sub.5, and have a molar ratio
(Al.sub.2O.sub.3+Na.sub.2O+P.sub.2O.sub.5)/SiO.sub.2 of 0.1 to 0.5,
a molar ratio (B.sub.2O.sub.3+Na.sub.2O)/SiO.sub.2 of 0.1 to 0.3, a
molar ratio P.sub.2O.sub.5/SiO.sub.2 of 0 to 0.2, a molar ratio
Al.sub.2O.sub.3/SiO.sub.2 of 0.05 to 0.3, and a molar ratio
Na.sub.2O/Al.sub.2O.sub.3 of 1 to 3.
[0017] Fifth, it is preferred that the tempered glass of the
present invention comprise, as a glass composition in terms of mol
%, 50 to 70% of SiO.sub.2, 5 to 11% of Al.sub.2O.sub.3, 0 to 1% of
B.sub.2O.sub.3, 0 to 2% of Li.sub.2O, 10 to 18% of Na.sub.20, 1 to
6% of K.sub.2O, 0 to 12% of MgO, 0 to 2.5% of CaO, 5 to 12% of
MgO+CaO, and 0 to 10% of P.sub.2O.sub.5, and have a molar ratio
(Al.sub.2O.sub.3+Na.sub.2O+P.sub.2O.sub.5)/SiO.sub.2 of 0.2 to 0.5,
a molar ratio (B.sub.2O.sub.3+Na.sub.2O)/SiO.sub.2 of 0.15 to 0.27,
a molar ratio P.sub.2O.sub.5/SiO.sub.2 of 0 to 0.1, a molar ratio
Al.sub.2O.sub.3/SiO.sub.2 of 0.07 to 0.2, and a molar ratio
Na.sub.2O/Al.sub.2O.sub.3 of 1 to 2.3.
[0018] Sixth, in the tempered glass of the present invention, it is
preferred that a surface roughness Ra of the etched surface be 1 nm
or less. Herein, the "surface roughness Ra" refers to a value
obtained by a measurement method in accordance with SEMI D7-94 "FPD
glass substrate surface roughness measurement method."
[0019] Seventh, in the tempered glass of the present invention, it
is preferred that a compression stress value of the compression
stress layer be 200 MPa or more, and a depth of the compression
stress layer be 10 .mu.m or more. Herein, the "compression stress
value of the compression stress layer" and the "depth of the
compression stress layer" refer to values which are calculated from
the number of interference fringes on a sample and each interval
between the interference fringes, the interference fringes being
observed when a surface stress meter (such as FSM-6000 manufactured
by Toshiba Corporation) is used to observe the sample.
[0020] Eighth, it is preferred that the tempered glass of the
present invention have an internal tensile stress of 1 to 200 MPa.
Herein, the "internal tensile stress" is calculated from the
following equation.
Internal tensile stress=(compression stress value.times.depth of
compression stress layer)/(sheet thickness-depth of compression
stress layer.times.2)
[0021] Ninth, it is preferred that the tempered glass of the
present invention have a liquidus temperature of 1,250.degree. C.
or less. Herein, the "liquidus temperature" refers to a temperature
at which crystals of glass are deposited after glass powder that
passes through a standard 30-mesh sieve (sieve opening: 500 .mu.m)
and remains on a 50-mesh sieve (sieve opening: 300 .mu.m) is placed
in a platinum boat and then kept for 24 hours in a gradient heating
furnace.
[0022] Tenth, it is preferred that the tempered glass of the
present invention have a liquidus viscosity of 10.sup.4.0 dPas or
more. Herein, the "liquidus viscosity" refers to a value obtained
through measurement of a viscosity of glass at the liquidus
temperature by a platinum sphere pull up method.
[0023] Eleventh, it is preferred that the tempered glass of the
present invention have a temperature at 10.sup.4.0 dPas of
1,280.degree. C. or less. Herein, the "temperature at 10.sup.4.0
dPas" refers to a value obtained through measurement by a platinum
sphere pull up method.
[0024] Twelfth, it is preferred that the tempered glass of the
present invention have a temperature at 10.sup.2.5 dPas of
1,620.degree. C. or less. Herein, the "temperature at 10.sup.2.5
dPas" refers to a value obtained through measurement by a platinum
sphere pull up method.
[0025] Thirteenth, it is preferred that the tempered glass of the
present invention have a density of 2.6 g/cm.sup.3 or less. Herein,
the "density" can be measured by a well-known Archimedes
method.
[0026] Fourteenth, it is preferred that the tempered glass of the
present invention be formed by a float method.
[0027] Fifteenth, it is preferred that the tempered glass of the
present invention be used for a touch panel display.
[0028] Sixteenth, it is preferred that the tempered glass of the
present invention be used for a cover glass for a cellular
phone.
[0029] Seventeenth, it is preferred that the tempered glass of the
present invention be used for a cover glass for a solar cell.
[0030] Eighteenth, it is preferred that the tempered glass of the
present invention be used for a protective member for a
display.
[0031] Nineteenth, a production method for a tempered glass of the
present invention is characterized by comprising: (1) a forming
step of melting glass raw materials blended so as to achieve a
glass composition comprising, in terms of mol %, 45 to 75% of
SiO.sub.2, 3 to 15% of Al.sub.2O.sub.3, 0 to 12% of Li.sub.2O, 0.3
to 20% of Na.sub.2O, 0 to 10% of K.sub.2O, and 1 to 15% of MgO+CaO,
followed by the formation of the molten glass into a glass sheet;
(2) a tempering step of forming a compression stress layer by
performing ion exchange treatment to yield a tempered glass; (3) a
masking step of masking a surface of the tempered glass; and (4) an
etching step of etching the tempered glass in an etching
liquid.
[0032] Twentieth, it is preferred that the production method for a
tempered glass of the present invention comprise a patterning step
of performing patterning on the surface of the tempered glass
before the masking step. With this, the production cost of a device
using the tempered glass significantly reduces. In this case, it is
preferred that masking be also performed on the surface of a
predetermined pattern formed on the surface of the tempered glass
in order to prevent the degradation of the pattern caused by the
subsequent etching.
[0033] Twenty-first, in the production method for a tempered glass
of the present invention, it is preferred that the etching step be
a step of separating the tempered glass into a plurality of small
tempered glass pieces. With this, a plurality of tempered glasses
each having a product shape can be produced from a large tempered
glass, and hence the production cost of devices using such tempered
glasses significantly reduces.
[0034] Twenty-second, in the production method for a tempered glass
of the present invention, it is preferred that the etching liquid
comprise one kind or two or more kinds selected from the group
consisting of HF, HCl, H.sub.2SO.sub.4, HNO.sub.3, NH.sub.4F, NaOH,
and NH.sub.4HF.sub.2. Note that those etching liquids each have
good performance for etching.
Advantageous Effects of Invention
[0035] The tempered glass of the present invention has the property
of being etched properly, and hence etching for a short time can
remove the parts excluding masked parts. As a result, each shape
necessary to be used in a cellular phone, a tablet PC, and the like
can be efficiently provided to each of the masked parts, and the
masked parts can each have high surface quality and high end
surface quality. In addition, the tempered glass of the present
invention has high ion exchange performance, thus having a high
mechanical strength and having a variation in mechanical strength
to a small extent. Further, the tempered glass of the present
invention has a low density, enabling production of a lighter
tablet PC, and has a high strain point, thus being able to undergo
a high-quality patterning.
BRIEF DESCRIPTION OF DRAWINGS
[0036] FIG. 1A is a conceptual diagram for describing the
experimental procedure in Example 2 of the present invention.
[0037] FIG. 1B is a conceptual diagram for further describing the
experimental procedure in Example 2 of the present invention.
[0038] FIG. 1C is a conceptual diagram for further describing the
experimental procedure in Example 2 of the present invention.
DESCRIPTION OF EMBODIMENTS
[0039] (1) Tempered Glass
[0040] A tempered glass according to an embodiment of the present
invention has a compression stress layer in a surface thereof.
Although a physical tempering method may be used as a method of
forming the compression stress layer in the surface, a chemical
tempering method is more preferably used. The chemical tempering
method is a method involving introducing alkali ions each having a
large ion radius into the surface layer of glass by ion exchange
treatment at a temperature equal to or lower than a strain point of
the glass. When the chemical tempering method is used to form a
compression stress layer, the compression stress layer can be
properly formed even in the case where the thickness of the glass
is small. In addition, even when a tempered glass is cut after the
formation of the compression stress layer, the tempered glass does
not easily break unlike a tempered glass produced by applying a
physical tempering method such as an air cooling tempering
method.
[0041] The tempered glass of this embodiment comprises, as a glass
composition in terms of mol %, 45 to 75% of SiO.sub.2, 3 to 15% of
Al.sub.2O.sub.3, 0 to 12% of B.sub.2O.sub.3, 0 to 12% of Li.sub.2O,
0.3 to 20% of Na.sub.2O, 0 to 10% of K.sub.2O, 1 to 15% of MgO+CaO,
and 0 to 10% of P.sub.2O.sub.5. The reason why the content range of
each component is limited as described above is described below.
Note that, unless specifically indicated, the expression "%" refers
to "mol %" in the following description of the content range of
each component.
[0042] SiO.sub.2 is a component that forms a network of glass. The
content of SiO.sub.2 is 45 to 75%, preferably 50 to 70%, 55 to 68%,
55 to 67%, particularly preferably 58 to 66%. When the content of
SiO.sub.2 is too small, vitrification does not occur easily, the
thermal expansion coefficient becomes too high, the thermal shock
resistance is liable to lower, and the rate of etching with an acid
such as HCl becomes too high, with the result that it is difficult
to obtain desired surface quality and desired end surface quality.
On the other hand, when the content of SiO.sub.2 is too large, the
meltability and formability are liable to lower, and the thermal
expansion coefficient becomes too low, with the result that it is
difficult to match the thermal expansion coefficient with those of
peripheral materials. In addition, the rate of etching becomes low
and hence the productivity of a device using the tempered glass is
liable to lower.
[0043] Al.sub.2O.sub.3 is a component that enhances the ion
exchange performance and is a component that enhances the strain
point or Young's modulus. The content of Al.sub.2O.sub.3 is 3 to
15%. When the content of Al.sub.2O.sub.3 is too small, the ion
exchange performance may not be exerted sufficiently. Thus, the
lower limit range of Al.sub.2O.sub.3 is suitably 4% or more, 5% or
more, 5.5% or more, 7% or more, 8% or more, particularly suitably
9% or more. On the other hand, when the content of Al.sub.2O.sub.3
is too large, devitrified crystals are liable to be deposited in
the glass, and it is difficult to form a glass sheet by a float
method, an overflow down-draw method, or the like. Further, the
thermal expansion coefficient becomes too low, and it is difficult
to match the thermal expansion coefficient with those of peripheral
materials. In addition, the viscosity at high temperature increases
and the meltability is liable to lower. In addition, the rate of
etching with an acid such as HCl becomes too high, and hence the
glass is difficult to have desired surface quality and desired end
surface quality. Thus, the upper limit range of Al.sub.2O.sub.3 is
suitably 13% or less, 12% or less, 11% or less, particularly
suitably 9% or less.
[0044] B.sub.2O.sub.3 is a component that lowers the viscosity at
high temperature and density, stabilizes glass so that a crystal
may be unlikely precipitated, and lowers the liquidus temperature.
However, when the content of B.sub.2O.sub.3 is too large, through
ion exchange, coloring on the surface of glass called weathering
occurs, water resistance lowers, the compression stress value of
the compression stress layer lowers, the depth of the compression
stress layer decreases, and the rate of etching with an acid such
as HCl becomes too high, with the result that the glass is
difficult to have desired surface quality and desired end surface
quality. Thus, the content of B.sub.2O.sub.3 is preferably 0 to
12%, 0 to 5%, 0 to 3%, 0 to 1.5%, 0 to 1%, 0 to 0.9%, 0 to 0.5%,
particularly preferably 0 to 0.1%.
[0045] Li.sub.2O is an ion exchange component, is a component that
lowers the viscosity at high temperature to increase the
meltability and formability, and is a component that increases the
Young's modulus. Further, Li.sub.2O has a great effect of
increasing the compression stress value among alkali metal oxides,
but when the content of Li.sub.2O becomes extremely large in a
glass system containing Na.sub.2O at 5% or more, the compression
stress value tends to lower to the worse. Further, when the content
of Li.sub.2O is too large, the liquidus viscosity lowers, the glass
is liable to denitrify, and the thermal expansion coefficient
becomes too high, with the result that the thermal shock resistance
lowers and it is difficult to match the thermal expansion
coefficient with those of peripheral materials. In addition, the
viscosity at low temperature becomes too low, and the stress
relaxation is liable to occur, with the result that the compression
stress value lowers to the worse in some cases. Thus, the content
of Li.sub.2O is 0 to 12%, preferably 0 to 8%, 0 to 4%, 0 to 2%, 0
to 1%, 0 to 0.5%, 0 to 0.3%, particularly preferably 0 to 0.1%.
[0046] Na.sub.2O is an ion exchange component and is a component
that lowers the viscosity at high temperature to increase the
meltability and formability. Na.sub.2O is also a component that
improves the denitrification resistance. The content of Na.sub.2O
is 0.3 to 20%. When the content of Na.sub.2O is too small, the
meltability lowers, the thermal expansion coefficient lowers, and
the ion exchange performance is liable to lower. In addition, the
rate of etching is low and hence the productivity of the device is
liable to lower. Thus, the lower limit range of Na.sub.2O is
suitably 5% or more, 8% or more, 9% or more, 10% or more, 11% or
more, particularly suitably 12% or more. On the other hand, when
the content of Na.sub.2O is too high, the thermal expansion
coefficient becomes too large, the thermal shock resistance lowers,
and it is difficult to match the thermal expansion coefficient with
those of peripheral materials. Further, the strain point lowers
excessively, and the glass composition loses its component balance,
with the result that the devitrification resistance lowers to the
worse in some cases. In addition, the rate of etching with an acid
such as HCl is too high, and hence the glass is difficult to have
desired surface quality and desired end surface quality. Thus, the
upper limit range of Na.sub.2O is suitably 19% or less, 18% or
less, 17% or less, particularly suitably 16% or less.
[0047] K.sub.2O is a component that promotes ion exchange and is a
component that allows the depth of the compression stress layer to
be easily increased among alkali metal oxides. K.sub.2O is also a
component that lowers the viscosity at high temperature to increase
the meltability and formability. K.sub.2O is also a component that
improves devitrification resistance. Thus, the content of K.sub.2O
is 0 to 10%. When the content of K.sub.2O is too high, the thermal
expansion coefficient becomes too large, the thermal shock
resistance lowers, and it is difficult to match the thermal
expansion coefficient with those of peripheral materials. Further,
the strain point lowers excessively, and the glass composition
loses its component balance, with the result that the
devitrification resistance tends to lower to the worse. Thus, the
upper limit range of K.sub.2O is suitably 8% or less, 7% or less,
6% or less, particularly suitably 5% or less. Note that, when
K.sub.2O is added to the glass composition, the lower limit range
of K.sub.2O is suitably 0.1% or more, 0.5% or more, 1% or more,
1.5% or more, 2% or more, particularly suitably 2.5% or more.
[0048] The content of Li.sub.2O+Na.sub.2O+K.sub.2O is preferably 5
to 25%, 8 to 22%, 12 to 20%, particularly preferably 16.5 to 20%.
When the content of Li.sub.2O+Na.sub.2O+K.sub.2O is too small, the
ion exchange performance and meltability are liable to deteriorate.
On the other hand, when the content of Li.sub.2O+Na.sub.2O+K.sub.2O
is too large, the glass is liable to denitrify and the thermal
expansion coefficient increases excessively, with the result that
the thermal shock resistance deteriorates and it is difficult to
match the thermal expansion coefficient with those of peripheral
materials. In addition, the strain point lowers excessively, with
the result that a high compression stress value is hardly achieved
in some cases. Moreover, the viscosity at around its liquidus
temperature lowers, with the result that the glass is difficult to
have a high liquidus viscosity in some cases. Note that the
"Li.sub.2O+Na.sub.2O+K.sub.2O" refers to the total amount of
Li.sub.2O, Na.sub.2O, and K.sub.2O.
[0049] MgO is a component that reduces the viscosity at high
temperature to enhance the meltability and formability, and
increases the strain point and Young's modulus, and is a component
that has a great effect of enhancing the ion exchange performance
among alkaline earth metal oxides. However, when the content of MgO
is too large, the density and thermal expansion coefficient
increase, and the glass is liable to devitrify. Thus, the upper
limit range of MgO is suitably 12% or less, 10% or less, 8% or
less, particularly suitably 7% or less. Note that, when MgO is
added to the glass composition, the lower limit range of MgO is
suitably 0.1% or more, 0.5% or more, 1% or more, 2% or more,
particularly suitably 3% or more.
[0050] CaO is a component that has great effects of reducing the
viscosity at high temperature to enhance the meltability and
formability, and increasing the strain point and Young's modulus
without causing any reduction in devitrification resistance as
compared to other components. The content of CaO is preferably 0 to
10%. However, when the content of CaO is too large, the density and
thermal expansion coefficient increase, and the glass composition
loses its component balance, with the results that the glass is
liable to devitrify to the worse, the ion exchange performance is
liable to lower, and phase separation is liable to occur. Thus, the
content of CaO is suitably 0 to 5%, 0 to 3%, particularly suitably
0 to 2.5%.
[0051] The content of MgO+CaO is 1 to 15%. When the content of
MgO+CaO is too small, the glass is difficult to have desired ion
exchange performance, the viscosity at high temperature increases,
and the melting temperature is liable to increase. On the other
hand, when the content of MgO+CaO is too large, the density and
thermal expansion coefficient increase, and the devitrification
resistance is liable to deteriorate. Thus, the content of MgO+CaO
is preferably 3 to 13%, 5 to 13%, 5 to 12%, particularly preferably
5 to 11%.
[0052] P.sub.2O.sub.5 is a component that enhances the ion exchange
performance and a component that increases the depth of the
compression stress layer, in particular. However, when the content
of P.sub.2O.sub.5 is too large, phase separation occurs in the
glass, the rate of etching with an acid such as HCl is too high,
and hence the glass is difficult to have desired surface quality
and desired end surface quality. Thus, the upper limit range of
P.sub.2O.sub.5 is suitably 10% or less, 5% or less, particularly
suitably 3% or less. Note that, when P.sub.2O.sub.5 is added to the
glass composition, the lower limit range of P.sub.2O.sub.5 is
suitably 0% or more, 0.01% or more, 0.1% or more, 0.5% or more,
particularly suitably 1% or more.
[0053] The tempered glass of this embodiment preferably has the
following component ratios.
[0054] A molar ratio
(Al.sub.2O.sub.3+Na.sub.2O+P.sub.2O.sub.5)/SiO.sub.2 is 0.1 to 1.
When the molar ratio
(Al.sub.2O.sub.3+Na.sub.2O+P.sub.2O.sub.5)/SiO.sub.2 is too small,
the rate of etching is low and hence the productivity of the device
is liable to lower. In addition, the ion exchange performance is
liable to deteriorate. On the other hand, when the molar ratio
(Al.sub.2O.sub.3+Na.sub.2O+P.sub.2O.sub.5)/SiO.sub.2 is too large,
the rate of etching with an acid such as HCl is too high, and hence
the glass is difficult to have desired surface quality and desired
end surface quality, the denitrification resistance deteriorates,
and the glass is difficult to have a high liquidus viscosity. Thus,
the lower limit range of the molar ratio
(Al.sub.2O.sub.3+Na.sub.2O+P.sub.2O.sub.5)/SiO.sub.2 is suitably
0.15 or more, 0.2 or more, particularly suitably 0.25 or more, and
the upper limit range thereof is suitably 0.7 or less, 0.5 or less,
particularly suitably 0.4 or less.
[0055] A molar ratio (B.sub.2O.sub.3+Na.sub.2O)/SiO.sub.2 is 0.1 to
1. When the molar ratio (B.sub.2O.sub.3+Na.sub.2O)/SiO.sub.2 is too
small, the rate of etching is low and hence the productivity of the
device is liable to lower. In addition, the viscosity at high
temperature increases, and hence the meltability deteriorates, with
the result that the bubble quality is liable to deteriorate. On the
other hand, when the molar ratio
(B.sub.2O.sub.3+Na.sub.2O)/SiO.sub.2 is too large, the rate of
etching with an acid such as HCl is too high, and hence the glass
is difficult to have desired surface quality and desired end
surface quality, the denitrification resistance deteriorates, and
the glass is difficult to have a high liquidus viscosity. Thus, the
lower limit range of the molar ratio
(B.sub.2O.sub.3+Na.sub.2O)/SiO.sub.2 is suitably 0.15 or more, 0.2
or more, particularly suitably 0.23 or more, and the upper limit
range thereof is suitably 0.7 or less, 0.5 or less, 0.4 or less,
0.3 or less, particularly suitably 0.27 or less.
[0056] A molar ratio P.sub.2O.sub.5/SiO.sub.2 is 0 to 1. When the
molar ratio P.sub.2O.sub.5/SiO.sub.2 is large, the compression
stress layer tends to have a large thickness. However, when the
value of the molar ratio is too large, the rate of etching with an
acid such as HCl is too high, and hence the glass is difficult to
have desired surface quality and desired end surface quality. Thus,
the range of the molar ratio P.sub.2O.sub.5/SiO.sub.2 is suitably 0
to 0.5, 0 to 0.3, 0 to 0.2, particularly suitably 0 to 0.1.
[0057] A molar ratio Al.sub.2O.sub.3/SiO.sub.2 is 0.01 to 1. When
the molar ratio Al.sub.2O.sub.3/SiO.sub.2 is larger, the strain
point and Young's modulus increase, and the ion exchange
performance can be enhanced. However, when the value of the molar
ratio is too large, devitrified crystals are liable to be deposited
in the glass, the glass is difficult to have a high liquidus
viscosity, the viscosity at high temperature increases, the
meltability is liable to deteriorate, the rate of etching with an
acid such as HCl is too high, and hence the glass is difficult to
have desired surface quality and desired end surface quality. Thus,
the range of the molar ratio Al.sub.2O.sub.3/SiO.sub.2 is suitably
0.01 to 0.7, 0.01 to 0.5, 0.05 to 0.3, particularly suitably 0.07
to 0.2.
[0058] A molar ratio Na.sub.2O/Al.sub.2O.sub.3 is 0.1 to 5. When
the molar ratio Na.sub.2O/Al.sub.2O.sub.3 is too small, the
denitrification resistance is liable to deteriorate and the melting
temperature is liable to increase. On the other hand, when the
molar ratio Na.sub.2O/Al.sub.2O.sub.3 is too large, the thermal
expansion coefficient becomes too high, the viscosity at high
temperature becomes too low, and hence the glass is difficult to
have a high liquidus viscosity. Thus, the range of the molar ratio
Na.sub.2O/Al.sub.2O.sub.3 is suitably 0.5 to 4, 1 to 3,
particularly suitably 1.2 to 2.3.
[0059] In addition to the components described above, for example,
the following components may be added.
[0060] SrO is a component that reduces the viscosity at high
temperature to increase the meltability and formability, and
increases the strain point and Young's modulus without causing any
reduction in devitrification resistance. When the content of SrO is
too large, the density and thermal expansion coefficient increase,
the ion exchange performance lowers, and the glass composition
loses its component balance, with the result that the glass is
liable to devitrify to the worse. The content of SrO is preferably
0 to 5%, 0 to 3%, 0 to 1%, particularly preferably 0 to 0.1%.
[0061] BaO is a component that reduces the viscosity at high
temperature to increase the meltability and formability, and
increases the strain point and Young's modulus without causing any
reduction in devitrification resistance. When the content of BaO is
too large, the density and thermal expansion coefficient increase,
the ion exchange performance lowers, and the glass composition
loses its component balance, with the result that the glass is
liable to devitrify to the worse. The content of BaO is preferably
0 to 5%, 0 to 3%, 0 to 1%, particularly preferably 0 to 0.1%.
[0062] TiO.sub.2 is a component that enhances the ion exchange
performance and is a component that reduces the viscosity at high
temperature. However, when the content of TiO.sub.2 is too large,
the glass is liable to be colored and to devitrify. Thus, the
content of TiO.sub.2 is preferably 0 to 3%, 0 to 1%, 0 to 0.8%, 0
to 0.5%, particularly preferably 0 to 0.1%.
[0063] ZrO.sub.2 is a component that remarkably enhances the ion
exchange performance, and is a component that increases the
viscosity around the liquidus viscosity and the strain point.
However, when the content of ZrO.sub.2 is too large, the
devitrification resistance may lower remarkably and the density may
increase excessively. Thus, the upper limit range of ZrO.sub.2 is
suitably 10% or less, 8% or less, 6% or less, 4% or less,
particularly suitably 3% or less. Note that, when the enhancement
of the ion exchange performance is intended, ZrO.sub.2 is
preferably added to the glass composition, and in this case, the
lower limit range of ZrO.sub.2 is suitably 0.01% or more, 0.1% or
more, 0.5% or more, 1% or more, particularly suitably 2% or
more.
[0064] ZnO is a component that enhances the ion exchange
performance and is a component that has a great effect of
increasing the compression stress value, in particular. Further,
ZnO is a component that reduces the viscosity at high temperature
without reducing the viscosity at low temperature. However, when
the content of ZnO is too large, the glass manifests phase
separation, the devitrification resistance lowers, the density
increases, and the depth of the compression stress layer tends to
decrease. Thus, the content of ZnO is preferably 0 to 6%, 0 to 5%,
0 to 3%, 0 to 1%, particularly preferably 0 to 0.5%.
[0065] As a fining agent, one kind or two or more kinds selected
from the group consisting of As.sub.2O.sub.3, Sb.sub.2O.sub.3,
CeO.sub.2, SnO.sub.2, F, Cl, and SO.sub.3 (preferably the group
consisting of SnO.sub.2, Cl, and SO.sub.3) may be added at 0 to 3%.
The content of SnO.sub.2+SO.sub.3+Cl is preferably 0 to 1%, 100 to
3,000 ppm, 300 to 2,500 ppm, particularly preferably 500 to 2,500
ppm. Note that, when the content of SnO.sub.2+SO.sub.3+Cl is less
than 100 ppm, it is difficult to obtain a fining effect. Herein,
the "SnO.sub.2+SO.sub.3+Cl" refers to the total amount of
SnO.sub.2, SO.sub.3, and Cl.
[0066] The tempered glass preferably contains As.sub.2O.sub.3,
Sb.sub.2O.sub.3, and F as little as possible, and is more
preferably substantially free of As.sub.2O.sub.3, Sb.sub.2O.sub.3,
and F from the standpoint of environmental considerations. Herein,
the gist of the phrase "substantially free of As.sub.2O.sub.3"
resides in that As.sub.2O.sub.3 is not added positively as a glass
component, but contamination with As.sub.2O.sub.3 as an impurity is
allowable. Specifically, the phrase means that the content of
As.sub.2O.sub.3 is less than 500 ppm (by mass). The gist of the
phrase "substantially free of Sb.sub.2O.sub.3" resides in that
Sb.sub.2O.sub.3 is not added positively as a glass component, but
contamination with Sb.sub.2O.sub.3 as an impurity is allowable.
Specifically, the phrase means that the content of Sb.sub.2O.sub.3
is less than 500 ppm (by mass). The gist of the phrase
"substantially free of F" resides in that F is not added positively
as a glass component, but contamination with F as an impurity is
allowable. Specifically, the phrase means that the content of F is
less than 500 ppm (by mass).
[0067] The content of Fe.sub.2O.sub.3 is preferably less than 500
ppm, less than 400 ppm, less than 300 ppm, less than 200 ppm,
particularly preferably less than 150 ppm. With this, the
transmittance (400 nm to 770 nm) of glass having a thickness of 1
mm is easily improved (for example, 90% or more).
[0068] A rare earth oxide such as Nb.sub.2O.sub.5 or
La.sub.2O.sub.3 is a component that increases the Young's modulus.
However, the cost of the raw material itself is high, and when the
rare earth oxide is added in a large amount, the denitrification
resistance is liable to lower. Thus, the content of the rare earth
oxide is preferably 3% or less, 2% or less, 1% or less, 0.5% or
less, particularly preferably 0.1% or less.
[0069] A transition metal element (such as Co or Ni) may reduce the
transmittance of glass because the element causes the intense
coloration of the glass. In particular, in the case where the glass
is used for a touch panel display, when the content of the
transition metal element is too large, the visibility of the touch
panel display is liable to lower. Thus, it is preferred to select a
glass raw material (including cullet) so that the content of a
transition metal oxide is 0.5% or less, 0.1% or less, particularly
0.05% or less.
[0070] The tempered glass is preferably substantially free of PbO
and Bi.sub.2O.sub.3 from environmental considerations. Herein, the
gist of the phrase "substantially free of PbO" resides in that PbO
is not added positively as a glass component, but contamination
with PbO as an impurity is allowable. Specifically, the phrase
means that the content of PbO is less than 500 ppm (by mass). The
gist of the phrase "substantially free of Bi.sub.2O.sub.3" resides
in that Bi.sub.2O.sub.3 is not added positively as a glass
component, but contamination with Bi.sub.2O.sub.3 as an impurity is
allowable. Specifically, the phrase means that the content of
Bi.sub.2O.sub.3 is less than 500 ppm (by mass).
[0071] It is possible to construct suitable glass composition
ranges by appropriately selecting suitable content ranges of the
respective components. Of those, as a particularly suitable glass
composition range, the tempered glass comprises, in terms of mol %,
50 to 70% of SiO.sub.2, 5.5 to 9% of Al.sub.2O.sub.3, 0 to 0.1% of
B.sub.2O.sub.3, 0 to 0.5% of Li.sub.2O, 12 to 17% of Na.sub.2O, 2
to 5% of K.sub.2O, 0 to 12% of MgO, 0 to 2.5% of CaO, and 5 to 11%
of MgO+CaO, and has a molar ratio
(Al.sub.2O.sub.3+Na.sub.2O+P.sub.2O.sub.5)/SiO.sub.2 of 0.25 to
0.5, a molar ratio (B.sub.2O.sub.3+Na.sub.2O)/SiO.sub.2 of 0.15 to
0.27, a molar ratio P.sub.2O.sub.5/SiO.sub.2 of 0 to 0.1, a molar
ratio Al.sub.2O.sub.3/SiO.sub.2 of 0.07 to 0.2, and a molar ratio
Na.sub.2O/Al.sub.2O.sub.3 of 1.2 to 2.3.
[0072] When the tempered glass of this embodiment is immersed in a
10-mass % HCl aqueous solution at 80.degree. C. for 24 hours, the
tempered glass preferably has a weight loss of 0.05 to 50
g/cm.sup.2. When the value of the weight loss of a tempered glass
is less than 0.05 g/cm.sup.2, the rate of etching with respect to
the tempered glass is low, and hence, even if the tempered glass
having a large size is subjected to patterning to form a touch
panel sensor or the like and to predetermined masking, followed by
etching in an etching liquid, it is difficult to produce individual
pieces each having a desired shape. On the other hand, when the
value of the weight loss of a tempered glass is more than 50
g/cm.sup.2, the rate of etching with an acid such as HCl with
respect to the tempered glass is too high, and hence the resultant
pieces are difficult to have desired surface quality and desired
end surface quality. Note that the lower limit range of the weight
loss is suitably 0.1 g/cm.sup.2 or more, particularly suitably 0.2
g/cm.sup.2 or more. Further, the upper limit range of the weight
loss is suitably 45 g/cm.sup.2 or less, 20 g/cm.sup.2 or less, 10
g/cm.sup.2 or less, 5 g/cm.sup.2 or less, 2 g/cm.sup.2 or less,
particularly suitably 1 g/cm.sup.2 or less.
[0073] The compression stress value of the compression stress layer
of the tempered glass of this embodiment is preferably 300 MPa or
more, 400 MPa or more, 500 MPa or more, 600 MPa or more, 700 MPa or
more, particularly preferably 800 MPa or more. As the compression
stress value becomes larger, the mechanical strength of the
tempered glass becomes higher. On the other hand, when an extremely
large compression stress is formed on the surface of the tempered
glass, micro cracks are generated on the surface, which may reduce
the mechanical strength of the tempered glass to the worse.
Further, a tensile stress inherent in the tempered glass may
extremely increase. Thus, the compression stress value of the
compression stress layer is preferably 1,500 MPa or less. Note that
there is a tendency that the compression stress value is increased
by increasing the content of Al.sub.2O.sub.3, TiO.sub.2, ZrO.sub.2,
MgO, or ZnO in the glass composition or by reducing the content of
SrO or BaO in the glass composition. Further, there is a tendency
that the compression stress value is increased by shortening a time
necessary for ion exchange or by decreasing the temperature of an
ion exchange solution.
[0074] The depth of the compression stress layer is preferably 10
.mu.m or more, 15 .mu.m or more, 20 .mu.m or more, particularly
preferably 25 .mu.m or more. As the depth of the compression stress
layer becomes larger, the tempered glass is more hardly cracked
even when the tempered glass has a deep flaw, and a variation in
mechanical strength of the tempered glass becomes smaller. On the
other hand, as the depth of the compression stress layer becomes
larger, it becomes more difficult to cut the tempered glass and
masked parts of the tempered glass may break at the time of
etching. Thus, the depth of the compression stress layer is
preferably 500 .mu.m or less, 200 .mu.m or less, 150 .mu.m or less,
90 .mu.m or less, 60 .mu.m or less, 50 .mu.m or less, 40 .mu.m or
less, 35 .mu.m or less, particularly preferably 30 .mu.m or less.
Note that there is a tendency that the depth of the compression
stress layer is increased by increasing the content of K.sub.2O or
P.sub.2O.sub.5 in the glass composition or by decreasing the
content of SrO or BaO in the glass composition. Further, there is a
tendency that the depth of the compression stress layer is
increased by lengthening a time necessary for ion exchange or by
increasing the temperature of an ion exchange solution.
[0075] The internal tensile stress of the tempered glass is
preferably 200 MPa or less, 150 MPa or less, 120 MPa or less, 100
MPa or less, 70 MPa or less, 50 MPa or less, 30 MPa or less, 25 MPa
or less, particularly preferably 22 MPa or less. As the internal
tensile stress of a tempered glass is larger, masked parts of the
tempered glass may break at the time of etching. However, when the
internal tensile stress of a tempered glass is extremely small, the
compression stress value of its compression stress layer and the
thickness thereof reduce. Thus, the internal tensile stress is
preferably 1 MPa or more, 5 MPa or more, 10 MPa or more, 15 MPa or
more.
[0076] The tempered glass of this embodiment has a density of
preferably 2.6 g/cm.sup.3 or less, particularly preferably 2.55
g/cm.sup.3 or less. As the density becomes smaller, the weight of
the tempered glass can be reduced more. Note that the density is
easily reduced by increasing the content of SiO.sub.2,
B.sub.2O.sub.3, or P.sub.2O.sub.5 in the glass composition or by
reducing the content of an alkali metal oxide, an alkaline earth
metal oxide, ZnO, ZrO.sub.2, or TiO.sub.2 in the glass
composition.
[0077] The tempered glass of this embodiment has a thermal
expansion coefficient of preferably 80 to
120.times.10.sup.-7/.degree. C., 85 to 110.times.10.sup.-7/.degree.
C., 90 to 110.times.10.sup.-7/.degree. C., particularly preferably
90 to 105.times.10.sup.-7/.degree. C. When the thermal expansion
coefficient is controlled within the above-mentioned ranges, it
becomes easy to match the thermal expansion coefficient with those
of members made of a metal, an organic adhesive, and the like, and
the members made of a metal, an organic adhesive, and the like are
easily prevented from being peeled off. Herein, the "thermal
expansion coefficient" refers to a value obtained through
measurement of an average thermal expansion coefficient in the
temperature range of 30 to 380.degree. C. with a dilatometer. Note
that the thermal expansion coefficient is easily increased by
increasing the content of an alkali metal oxide or an alkaline
earth metal oxide in the glass composition, and in contrast, the
thermal expansion coefficient is easily decreased by reducing the
content of the alkali metal oxide or the alkaline earth metal
oxide.
[0078] The tempered glass of this embodiment has a strain point of
preferably 500.degree. C. or more, 520.degree. C. or more,
530.degree. C. or more, 550.degree. C. or more, particularly
preferably 570.degree. C. or more. As the strain point becomes
higher, the heat resistance is improved more, and the disappearance
of the compression stress layer more hardly occurs when the
tempered glass is subjected to thermal treatment. Further, as the
strain point becomes higher, stress relaxation more hardly occurs
during ion exchange treatment, and thus the compression stress
value can be maintained more easily. Further, a high-quality film
can be easily formed in patterning to form a touch panel sensor or
the like. Note that the strain point is easily increased by
increasing the content of an alkaline earth metal oxide,
Al.sub.2O.sub.3, ZrO.sub.2, or P.sub.2O.sub.5 in the glass
composition or by reducing the content of an alkali metal oxide in
the glass composition.
[0079] The tempered glass of this embodiment has a temperature at
10.sup.4.0 dPas of preferably 1,280.degree. C. or less,
1,230.degree. C. or less, 1,200.degree. C. or less, 1,180.degree.
C. or less, particularly preferably 1,160.degree. C. or less. As
the temperature at 10.sup.4.0 dPas becomes lower, a burden on
forming equipment is reduced more, the forming equipment has a
longer life, and consequently, the production cost of the tempered
glass is more likely to be reduced. Note that the temperature at
10.sup.4.0 dPas is easily decreased by increasing the content of an
alkali metal oxide, an alkaline earth metal oxide, ZnO,
B.sub.2O.sub.3, or TiO.sub.2 or by reducing the content of
SiO.sub.2 or Al.sub.2O.sub.3.
[0080] The tempered glass of this embodiment has a temperature at
10.sup.2.5 dPas of preferably 1,620.degree. C. or less,
1,550.degree. C. or less, 1,530.degree. C. or less, 1,500.degree.
C. or less, particularly preferably 1,450.degree. C. or less. As
the temperature at 10.sup.2.5 dPas becomes lower, melting at lower
temperature can be carried out, and hence a burden on glass
production equipment such as a melting furnace is reduced more, and
the bubble quality is easily improved more. That is, as the
temperature at 10.sup.2.5 dPas becomes lower, the production cost
of the tempered glass is more likely to be reduced. Note that the
temperature at 10.sup.2.5 dPas corresponds to a melting
temperature. Further, the temperature at 10.sup.2.5 dPas is easily
decreased by increasing the content of an alkali metal oxide, an
alkaline earth metal oxide, ZnO, B.sub.2O.sub.3, or TiO.sub.2 in
the glass composition or by reducing the content of SiO.sub.2 or
Al.sub.2O.sub.3 in the glass composition.
[0081] The tempered glass of this embodiment has a liquidus
temperature of preferably 1,200.degree. C. or less, 1,150.degree.
C. or less, 1,100.degree. C. or less, 1,050.degree. C. or less,
1,000.degree. C. or less, 950.degree. C. or less, 900.degree. C. or
less, particularly preferably 880.degree. C. or less. Note that as
the liquidus temperature becomes lower, the denitrification
resistance and formability are improved more. Further, the liquidus
temperature is easily decreased by increasing the content of
Na.sub.2O, K.sub.2O, or B.sub.2O.sub.3 in the glass composition or
by reducing the content of Al.sub.2O.sub.3, Li.sub.2O, MgO, ZnO,
TiO.sub.2, or ZrO.sub.2 in the glass composition.
[0082] The tempered glass of this embodiment has a liquidus
viscosity of preferably 10.sup.4.0 dPas or more, 10.sup.4.4 dPas or
more, 10.sup.4.8 dPas or more, 10.sup.5.0 dPas or more, 10.sup.5.4
dPas or more, 10.sup.5.6 dPas or more, 10.sup.6.0 dPas or more,
10.sup.6.2 dPas or more, particularly preferably 10.sup.6.3 dPas or
more. Note that, as the liquidus viscosity becomes higher, the
denitrification resistance and formability are improved more.
Further, the liquidus viscosity is easily increased by increasing
the content of Na.sub.2O or K.sub.2O in the glass composition or by
reducing the content of Al.sub.2O.sub.3, Li.sub.2O, MgO, ZnO,
TiO.sub.2, or ZrO.sub.2 in the glass composition.
[0083] The tempered glass of this embodiment has a surface
roughness Ra of surfaces of excluding etched surfaces of preferably
1 nm or less, 0.5 nm or less, 0.3 nm or less, particularly
preferably 0.2 nm or less. When the surface roughness Ra of the
surfaces excluding the etched surfaces is too large, not only the
appearance quality of the tempered glass deteriorates but also the
mechanical strength thereof may deteriorate.
[0084] The tempered glass of this embodiment has a surface
roughness Ra of the etched surfaces (the surface and the end
surfaces) of preferably 1 nm or less, 0.5 nm or less, 0.3 nm or
less, particularly preferably 0.2 nm or less. When the surface
roughness Ra of the etched surfaces is too large, not only the
appearance quality of the tempered glass deteriorates but also the
mechanical strength thereof may deteriorate.
[0085] The tempered glass of this embodiment has a thickness (sheet
thickness in the case of a sheet shape) of preferably 3.0 mm or
less, 2.0 mm or less, 1.5 mm or less, 1.3 mm or less, 1.1 mm or
less, 1.0 mm or less, 0.8 mm or less, particularly preferably 0.7
mm or less. On the other hand, when the thickness is too small, a
desired mechanical strength is hardly provided. Thus, the thickness
is preferably 0.1 mm or more, 0.2 mm or more, 0.3 mm or more,
particularly preferably 0.4 mm or more.
[0086] (2) Glass to be Tempered
[0087] A glass to be tempered according to an embodiment of the
present invention is characterized by comprising, as a glass
composition in terms of mol %, 45 to 75% of SiO.sub.2, 3 to 15% of
Al.sub.2O.sub.3, 0 to 12% of B.sub.2O.sub.3, 0 to 12% of Li.sub.2O,
0.3 to 20% of Na.sub.2O, 0 to 10% of K.sub.2O, 1 to 15% of MgO+CaO,
and 0 to 10% of P.sub.2O.sub.5, and having a molar ratio
(Al.sub.2O.sub.3+Na.sub.2O+P.sub.2O.sub.5)/SiO.sub.2 of 0.1 to 1, a
molar ratio (B.sub.2O.sub.3+Na.sub.2O)/SiO.sub.2 of 0.1 to 1, a
molar ratio P.sub.2O.sub.5/SiO.sub.2 of 0 to 1, a molar ratio
Al.sub.2O.sub.3/SiO.sub.2 of 0.01 to 1, and a molar ratio
Na.sub.2O/Al.sub.2O.sub.3 of 0.1 to 5. Herein, the term "glass to
be tempered" refers to a glass before tempering treatment
(untempered glass). The technical features of the glass to be
tempered are the same as those of the tempered glass described
above. Herein, the description thereof is omitted for convenience
sake.
[0088] When the glass to be tempered of this embodiment is immersed
in a KNO.sub.3 molten salt at 430.degree. C. for 4 hours, it is
preferred that the compression stress value of a compression stress
layer in a surface thereof be 300 MPa or more and the depth of the
compression stress layer be 10 .mu.m or more, it is more preferred
that the compression stress of the surface thereof be 600 MPa or
more and the depth of the compression stress layer be 15 .mu.m or
more, and it is still more preferred that the compression stress of
the surface thereof be 700 MPa or more and the depth of the
compression stress layer be 20 .mu.m or more.
[0089] When ion exchange treatment is performed, the temperature of
the KNO.sub.3 molten salt is preferably 400 to 550.degree. C., and
the ion exchange time is preferably 2 to 10 hours, particularly
preferably 4 to 8 hours. With this, the compression stress layer
can be properly formed easily. Note that the glass to be tempered
of this embodiment has the above-mentioned glass composition, and
hence the compression stress value and depth of the compression
stress layer can be increased without using a mixture of a
KNO.sub.3 molten salt and an NaNO.sub.3 molten salt or the
like.
[0090] When the glass to be tempered of this embodiment is treated
in a 5-mass % HF aqueous solution at 25.degree. C. for 10 minutes,
the surface roughness Ra of the etched surfaces is preferably 1 nm
or less, 0.5 nm or less, 0.3 nm or less, particularly preferably
0.2 nm or less. When the surface roughness Ra of the etched
surfaces is too large, not only the appearance quality of the
tempered glass deteriorates but also the mechanical strength
thereof may deteriorate.
[0091] When the glass to be tempered of this embodiment is immersed
in a 10-mass % HCl aqueous solution at 80.degree. C. for 24 hours,
the glass to be tempered preferably has a weight loss of 0.05 to 50
g/cm.sup.3. When the weight loss is excessively small, the rate of
etching is low and hence the productivity of the device is liable
to lower. On the other hand, when the weight loss is excessively
large, the rate of etching with an acid such as HCl is too high,
and hence the glass is difficult to have desired surface quality
and desired end surface quality. The lower limit range of the
weight loss is suitably 0.1 g/cm.sup.2 or more, particularly
suitably 0.2 g/cm.sup.2 or more. Further, the upper limit range of
the weight loss is suitably 45 g/cm.sup.2 or less, 20 g/cm.sup.2 or
less, 10 g/cm.sup.2 or less, 5 g/cm.sup.2 or less, 2 g/cm.sup.2 or
less, particularly suitably 1 g/cm.sup.2 or less.
[0092] (3) Tempered Glass and Production for Tempered Glass
[0093] The above-mentioned glass to be tempered and tempered glass
can be produced, for example, in the following manner.
[0094] First, glass raw materials blended so as to have the
above-mentioned glass composition are loaded into a continuous
melting furnace, melted under heating at 1,500 to 1,600.degree. C.,
and fined. After that, the molten glass is cast into a forming
apparatus to form a sheet-shaped glass or the like, followed by
annealing. Thus, a glass to be tempered having a sheet shape or the
like can be produced.
[0095] A float method is preferably adopted as a method of forming
molten glass into a sheet-shaped glass. The float method is
advantageous for mass production and upsizing.
[0096] Any of various forming methods except the float method may
be adopted. It is possible to adopt a forming method such as an
overflow down-draw method, a down-draw method (such as a slot down
method or a re-draw method), a roll out method, or a press
method.
[0097] Next, the resultant glass to be tempered can be subjected to
tempering treatment to produce a tempered glass. When the tempered
glass is processed into pieces each having a shape with a
predetermined size, it is preferred, from the viewpoint of better
productivity, that a large glass sheet be subjected to tempering
treatment, and the resultant tempered glass sheet be then subjected
to patterning to form a touch panel sensor or the like and to
predetermined masking, followed by etching in an etching liquid,
thereby producing individual pieces each having a desired
shape.
[0098] Ion exchange treatment is preferably used as the tempering
treatment. Conditions for the ion exchange treatment are not
particularly limited, and optimum conditions may be selected in
view of, for example, the viscosity properties, applications,
thickness, and internal tensile stress of glass. The ion exchange
treatment can be performed, for example, by immersing the glass to
be tempered in a KNO.sub.3 molten salt at 400 to 550.degree. C. for
1 to 8 hours. Particularly when the ion exchange of K ions in the
KNO.sub.3 molten salt with Na components in the glass is performed,
it is possible to form efficiently a compression stress layer.
[0099] Next, it is preferred that part of the surface of the
resultant tempered glass be subjected to masking so as to have a
desired shape (shape necessary to be used in a protective member
for a cellular phone, a tablet PC, or the like), followed by
etching in an etching liquid. The etching liquid is preferably an
etching liquid comprising one kind or two or more kinds selected
from the group consisting of HF, HCl, H.sub.2SO.sub.4, HNO.sub.3,
NH.sub.4F, NaOH, and NH.sub.4HF.sub.2, in particular, one kind or
two or more kinds selected from the group consisting of HCl, HF,
and HNO.sub.3. An aqueous solution having a concentration of
preferably 1 to 20 mass %, 2 to 10 mass %, particularly preferably
3 to 8 mass % is used as the etching liquid. The temperature of the
etching liquid used is preferably 20 to 50.degree. C., 20 to
40.degree. C., 20 to 30.degree. C., except for the case of using
HF. The time of the etching is preferably 1 to 20 minutes, 2 to 15
minutes, particularly preferably 3 to 10 minutes. When such etching
is performed, a desired shape can be provided without the
performance of a cutting process, an end surface process, a
drilling process, and the like after tempering treatment. In this
case, it is preferred that the tempered glass be separated into a
plurality of small pieces.
[0100] Note that the step of patterning on a surface of the
tempered glass may be performed before the performance of the step
of masking the tempered glass. With this, patterning can be
collectively applied onto the small pieces to be obtained, which
can contribute to decreasing the production cost of a device using
the tempered glass.
EXAMPLES
Example 1
[0101] Hereinafter, examples of the present invention are
described. Note that the following examples are merely
illustrative. The present invention is by no means limited to the
following examples.
[0102] Tables 1 to 3 show Examples of the present invention
(Samples Nos. 1 to 21). Note that, in the tables, the term "Not
measured" means that measurement has not yet been performed.
TABLE-US-00001 TABLE 1 Examples No. 1 No. 2 No. 3 No. 4 No. 5 No. 6
No. 7 Glass SiO.sub.2 61.1 60.3 61.6 61.4 61.1 57.4 58.7
composition Al.sub.2O.sub.3 12.9 13.0 9.8 11.0 12.3 13.3 13.1 (mol
%) MgO 6.5 6.6 6.6 6.6 6.5 6.7 6.7 CaO -- -- -- -- -- -- --
B.sub.2O.sub.3 -- -- -- -- -- -- -- ZrO.sub.2 -- -- -- -- -- 1.1
1.1 Li.sub.2O -- -- -- -- -- -- -- Na.sub.2O 15.9 16.0 16.1 16.0
16.0 16.4 16.2 K.sub.2O 3.5 3.5 3.5 3.5 3.5 3.6 3.6 P.sub.2O.sub.5
-- 0.5 2.3 1.4 0.5 1.4 0.5 SnO.sub.2 -- 0.1 0.1 0.1 0.1 0.1 0.1
SO.sub.3 0.03 -- -- -- -- -- -- Cl 0.07 -- -- -- -- -- -- Mg + Ca
6.5 6.6 6.6 6.6 6.5 6.7 6.6 (Al + Na + P)/Si 0.5 0.5 0.5 0.5 0.5
0.5 0.5 (B + Na)/Si 0.26 0.27 0.26 0.26 0.26 0.29 0.28 P/Si 0 0.008
0.038 0.023 0.008 0.025 0.008 Al/Si 0.2 0.2 0.2 0.2 0.2 0.2 0.2
Na/Al 1.2 1.2 1.6 1.5 1.3 1.2 1.2 .rho. (g/cm.sup.3) 2.47 2.48 2.46
2.47 2.47 2.51 2.51 .alpha. (.times.10.sup.-7/.degree. C.) 102 102
110 105 103 104 101 Ps (.degree. C.) 585 584 553 553 575 600 602 Ta
(.degree. C.) 634 832 602 600 623 648 651 Ts (.degree. C.) 866 865
855 833 854 876 879 10.sup.4.0 dPa s (.degree. C.) 1,225 1,226
1,176 1,197 1,214 1,214 1,219 10.sup.3.0 dPa s (.degree. C.) 1,412
1,412 1,369 1,388 1,400 1,388 1,395 10.sup.2.5 dPa s (.degree. C.)
1,528 1,529 1,489 1,507 1,515 1,497 1,505 TL (.degree. C.) 1,150
1,150 1,090 1,040 1,120 1,088 1,140 log.sub.10.eta..sub.TL (dPa s)
4.5 4.3 4.7 5.2 4.7 5.0 4.6 CS (MPa) 1,035 1,007 772 822 939 1,102
1,115 DOL (.mu.m) 19 20 23 21 20 20 18 Internal tensile 25 26 23 23
25 28 27 stress (MPa) Weight loss caused 40.1 40.2 0.4 17.7 Not Not
Not by HCl (g/cm.sup.2) measured measured measured
TABLE-US-00002 TABLE 2 Examples No. 8 No. 9 No. 10 No. 11 No. 12
No. 13 No. 14 Glass SiO.sub.2 60.4 65.0 64.2 63.5 62.9 62.3 60.7
composition Al.sub.2O.sub.3 11.7 9.5 10.2 10.8 9.7 10.3 10.5 (mol
%) MgO 6.6 6.4 6.4 6.4 6.5 6.5 6.6 CaO -- -- -- -- -- -- --
B.sub.2O.sub.3 -- -- -- -- -- -- -- ZrO.sub.2 1.1 -- -- -- -- -- --
Li.sub.2O -- -- -- -- -- -- -- Na.sub.2O 16.1 15.6 15.7 15.7 15.9
15.9 16.2 K.sub.2O 3.5 3.4 3.4 3.5 3.5 3.5 3.5 P.sub.2O.sub.5 0.5
-- -- -- 1.4 1.4 2.4 SnO.sub.2 0.1 -- -- -- 0.1 0.1 0.1 SO.sub.3 --
0.07 0.01 -- -- -- -- Cl -- 0.03 0.09 0.10 -- -- -- Mg + Ca 6.6 6.4
6.4 6.4 6.5 6.5 6.6 (Al + Na + P)/Si 0.5 0.4 0.4 0.4 0.4 0.4 0.5 (B
+ Na)/Si 0.27 0.24 0.24 0.25 0.25 0.26 0.27 P/Si 0.008 0 0 0 0.022
0.022 0.039 Al/Si 0.2 0.1 0.2 0.2 0.2 0.2 0.2 Na/Al 1.4 1.6 1.5 1.5
1.6 1.5 1.5 .rho. (g/cm.sup.3) 2.50 2.46 2.46 2.46 2.46 2.46 2.46
.alpha. (.times.10.sup.-7/.degree. C.) 101 101 102 102 103 103 110
Ps (.degree. C.) 586 540 548 558 541 549 564 Ta (.degree. C.) 634
585 595 606 587 596 614 Ts (.degree. C.) 862 811 822 834 824 832
868 10.sup.4.0 dPa s (.degree. C.) 1,208 1,182 1,192 1,203 1,182
1,189 1,189 10.sup.3.0 dPa s (.degree. C.) 1,387 1,380 1,387 1,398
1,376 1,381 1,379 10.sup.2.5 dPa s (.degree. C.) 1,500 1,505 1,510
1,522 1,499 1,504 1,498 TL (.degree. C.) 1,080 Not 980 1,000 1,110
1,050 Not measured measured log.sub.10.eta..sub.TL (dPa s) 5.0 Not
5.7 5.6 4.5 5.0 Not measured measured CS (MPa) 1,031 882 757 769
870 826 852 DOL (.mu.m) 19 19 21 19 18 21 22 Internal tensile 25 22
21 19 21 22 25 stress (MPa) Weight loss caused Not Not 0.52 0.12
0.45 1.02 0.55 by HCl (g/cm.sup.2) measured measured
TABLE-US-00003 TABLE 3 Examples No. 15 No. 16 No. 17 No. 18 No. 19
No. 20 No. 21 Glass SiO.sub.2 59.8 61.4 62.6 61.1 65.8 62.1 63.92
composition Al.sub.2O.sub.3 11.2 9.8 11.5 11.6 10.6 11.4 8.4 (mol
%) MgO 6.7 6.6 6.5 6.6 4.7 6.6 3.3 CaO -- -- -- -- -- -- 2.4
B.sub.2O.sub.3 -- -- -- -- 0.6 -- -- ZrO.sub.2 -- 1.1 -- 1.1 -- --
2.4 Li.sub.2O -- -- -- -- -- -- 0.2 Na.sub.2O 16.2 16.1 15.8 16.0
13.3 15.0 15.4 K.sub.2O 3.6 3.5 3.5 3.5 2.7 3.5 3.9 P.sub.2O.sub.5
2.4 1.4 -- -- 2.2 1.4 -- SnO.sub.2 0.1 0.1 -- -- 0.1 -- -- SO.sub.3
-- -- 0.05 0.08 -- -- 0.08 Cl -- -- 0.05 0.02 -- -- -- Mg + Ca 6.7
6.6 6.5 6.5 4.7 6.6 5.6 (Al + Na + P)/Si 0.5 0.4 0.4 0.5 0.4 0.4
0.37 (B + Na)/Si 0.27 0.26 0.25 0.26 0.21 0.24 0.24 P/Si 0.039
0.023 0 0 0.034 0.023 0.001 Al/Si 0.2 0.2 0.2 0.2 0.2 0.2 0.13
Na/Al 1.5 1.6 1.4 1.4 1.3 1.3 1.83 .rho. (g/cm.sup.3) 2.46 2.49
2.47 2.50 2.42 2.46 2.54 .alpha. (.times.10.sup.-7/.degree. C.) 109
102 102 103 93 102 102 Ps (.degree. C.) 574 562 567 586 585 570 533
Ta (.degree. C.) 624 610 614 635 639 619 576 Ts (.degree. C.) Not
844 844 862 932 867 793 measured 10.sup.4.0 dPa s (.degree. C.)
1,193 1,183 1,208 1,209 1,280 1,227 1,142 10.sup.3.0 dPa s
(.degree. C.) 1,382 1,366 1,398 1,390 1,484 1,421 1,319 10.sup.2.5
dPa s (.degree. C.) 1,500 1,482 1,517 1,505 1,612 1,542 1,431 TL
(.degree. C.) Not Not Not Not Not Not 880 measured measured
measured measured measured measured log.sub.10.eta..sub.TL (dPa s)
Not Not Not Not Not Not 6.4 measured measured measured measured
measured measured CS (MPa) 855 850 921 1,068 783 878 904 DOL
(.mu.m) 24 20 19 17 22 21 14 Internal tensile 27 22 23 24 23 24 16
stress (MPa) Weight loss caused Not Not Not Not Not Not 0.3 by HCl
(g/cm.sup.2) measured measured measured measured measured
measured
[0103] Each of the samples in the tables was produced as described
below. First, glass raw materials were blended so as to have glass
compositions shown in the tables, and melted at 1,580.degree. C.
for 8 hours using a platinum pot. After that, the resultant molten
glass was cast on a carbon plate and formed into a sheet shape. The
resultant glass sheet was evaluated for its various properties.
Note that a product processed into a glass sheet having a thickness
of 0.8 mm was used as a sample for the measurement of tempering
properties.
[0104] The density .rho. is a value obtained through measurement by
a well-known Archimedes method.
[0105] The thermal expansion coefficient .alpha. is a value
obtained through measurement of an average thermal expansion
coefficient in the temperature range of 30 to 380.degree. C. using
a dilatometer.
[0106] The strain point Ps and the annealing point Ta are values
obtained through measurement based on a method of ASTM C336.
[0107] The softening point Ts is a value obtained through
measurement based on a method of ASTM C338.
[0108] The temperatures at the high temperature viscosities of
10.sup.4.0 dPas, 10.sup.3.0 dPas, and 10.sup.2.5 dPas are values
obtained through measurement by a platinum sphere pull up
method.
[0109] The liquidus temperature TL is a value obtained through
measurement of a temperature at which crystals of glass are
deposited after glass powder that passes through a standard 30-mesh
sieve (sieve opening: 500 .mu.m) and remains on a 50-mesh sieve
(sieve opening: 300 .mu.m) is placed in a platinum boat and then
kept for 24 hours in a gradient heating furnace.
[0110] The liquidus viscosity log.sub.10.eta..sub.TL is a value
obtained through measurement of a viscosity of glass at the
liquidus temperature by a platinum sphere pull up method.
[0111] The weight loss of glass caused by an HCl aqueous solution
was evaluated as described below. First, each of the samples was
processed into a strip shape measuring 20 mm by 50 mm by 1 mm and
then sufficiently washed with isopropyl alcohol. Next, each of the
resultant samples was dried and its mass was measured. Further, 100
ml of a 10-mass % HCl aqueous solution were prepared and were
poured into a Teflon (trademark) bottle, and then the temperature
was adjusted to 80.degree. C. Subsequently, each of the samples
after the drying was immersed in the 10-mass % HCl aqueous solution
for 24 hours, whereby its surface and end surfaces were etched.
Finally, the mass of each of the etched samples was measured, and
then the weight loss of each of the samples was divided by the
surface area thereof. Thus, the weight loss per unit area was
calculated.
[0112] As evident from Tables 1 to 3, each of Samples Nos. 1 to 21
was found to be suitable as a material for a tempered glass, i.e.,
a glass to be tempered because each of the samples had a density
.rho. of 2.54 g/cm.sup.3 or less and a thermal expansion
coefficient .alpha. of 93 to 110.times.10.sup.-7/.degree. C.
Further, each of Samples Nos. 1 to 21 has a liquidus viscosity
log.sub.10.eta..sub.TL of 10.sup.4.3 dPas or more, and hence can be
formed into a sheet shape. Further, each of the samples has a
temperature at 10.sup.4.0 dPas of 1,280.degree. C. or less, and
hence does not impose a large burden on forming equipment.
Moreover, each of the samples has a temperature at 10.sup.2.5 dPas
of 1,612.degree. C. or less, and hence is expected to allow a large
number of glass sheets to be produced at low cost with high
productivity. Note that the glass compositions in a surface layer
before and after tempering treatment are different from each other
microscopically, but the glass composition of the whole glass is
not substantially changed before and after the tempering
treatment.
[0113] Subsequently, both surfaces of each of the samples for the
measurement of tempering properties were subjected to optical
polishing, and then subjected to ion exchange treatment including
immersion in a KNO.sub.3 molten salt at 420.degree. C. for 1.5
hours. Subsequently, after the ion exchange treatment, each of the
samples was washed. Then, the stress compression value CS and
thickness DOL of a compression stress layer were calculated from
the number of interference fringes and each interval between the
interference fringes, the interference fringes being observed with
a surface stress meter (FSM-6000 manufactured by Toshiba
Corporation). In the calculation, the refractive index and optical
elastic constant of each of the measurement samples were set to
1.52 and 28 [(nm/cm)/MPa], respectively.
[0114] Further, the internal tensile stress of the tempered glass
was calculated by using the following equation.
Internal tensile stress=(compression stress value.times.depth of
compression stress layer)/(sheet thickness-depth of compression
stress layer.times.2)
[0115] As evident from Tables 1 to 3, when each of Samples Nos. 1
to 21 was subjected to ion exchange treatment in a KNO.sub.3 molten
salt, the compression stress value CS of the compression stress
layer was found to be 757 MPa or more, the thickness DOL was found
to be 14 .mu.m or more, and the internal tensile stress was found
to be 16 to 28 MPa.
Example 2
[0116] Glass raw materials blended so as to achieve the glass
composition described in Sample No. 21 were fed into a continuous
melting furnace and were melted under heating, followed by fining.
After that, the resultant molten glass was formed into a glass
sheet having a thickness of 0.8 mm by a float method. Subsequently,
the glass sheet obtained was processed into a glass sheet having a
size of 1 m by 1.2 m, and then ion exchange treatment was performed
by immersing the sheet in a KNO.sub.3 molten salt at 420.degree. C.
for 2 hours.
[0117] After a rectangular ITO patterning (for the XY directions)
was performed as illustrated in FIG. 1A with respect to the
resultant tempered glass, a patterning for forming an insulating
film was performed as illustrated in FIG. 1B and a
metal-film-bridge patterning (in the Y direction) was then
performed as illustrated in FIG. 1C. Thus, a touch panel sensor was
formed on the tempered glass.
[0118] Subsequently, masking with Au was performed so that each
resultant glass piece measured 170 mm by 100 mm (R=7 mm at each
corner part). Next, the tempered glass with the touch panel sensor
and the Au masking was immersed in a 48-mass % HF aqueous solution
(30.degree. C.) for 30 minutes, yielding a plurality of tempered
glass pieces. Further, the Au on each surface thereof was removed
by etching. Thus, tempered glasses with a touch panel sensor were
yielded.
[0119] The surface roughness Ra of a surface (surface on which no
touch panel sensor was formed) of each of the tempered glass pieces
yielded and the surface roughness Ra of each end surface thereof
were measured. As a result, it was found that the surface roughness
Ra of the surface was 0.0003 .mu.m and the surface roughness Ra of
the end surface was 0.0021 .mu.m. Note that the term "surface
roughness Ra" refers to a value obtained by a measurement method in
accordance with SEMI D7-94 "FPD glass substrate surface roughness
measurement method."
INDUSTRIAL APPLICABILITY
[0120] The tempered glass of the present invention is suitable for
a cover glass for a cellular phone, a digital camera, a PDA, or the
like, or a substrate for a touch panel display or the like.
Further, the tempered glass of the present invention can be
expected to find use in applications requiring a high mechanical
strength, for example, a window glass, a substrate for a magnetic
disk, a substrate for a flat panel display, a cover glass for a
solar cell, a cover glass for a solid image pick-up element, and
tableware, in addition to the above-mentioned applications.
* * * * *